Expose shell type to extensions (#238071)

* copy everything from #237624

* try to better word notes in proposed.d.ts

* why is test being so flaky

* try sending one more text

* strictEqual only on isInteractedWith always fails

* update the name as recommended

* embed to make sure we are selecting event we are interested in as recommended

* add node as part of TerminalShellType

* getting type ..extHostTypes.TerminalShellType.Bash is not comparable to type ..vscode.TerminalShellType.Bash

* just use one enum?

* figured out how to get from extHostTypes

* clean up

src/vscode-dts/vscode.proposed.terminalShellType.d.ts

@@ -0,0 +1,40 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+declare module 'vscode' {
+
+	// https://github.com/microsoft/vscode/issues/230165
+
+	/**
+	 * Known terminal shell types.
+	 */
+	export enum TerminalShellType {
+		Sh = 1,
+		Bash = 2,
+		Fish = 3,
+		Csh = 4,
+		Ksh = 5,
+		Zsh = 6,
+		CommandPrompt = 7,
+		GitBash = 8,
+		PowerShell = 9,
+		Python = 10,
+		Julia = 11,
+		NuShell = 12,
+		Node = 13
+	}
+
+	// Part of TerminalState since the shellType can change multiple times and this comes with an event.
+	export interface TerminalState {
+		/**
+		 * The current detected shell type of the terminal. New shell types may be added in the
+		 * future in which case they will be returned as a number that is not part of
+		 * {@link TerminalShellType}.
+		 * Includes number type to prevent the breaking change when new enum members are added?
+		 */
+		readonly shellType?: TerminalShellType | number | undefined;
+	}
+
+}